What I normally do when I have an exception, I look for registers with addresses in the flash range, 0x8000000 and up ( for STMF32 ).
Then I open the LSS listing of the project and look up these addresses. When an addresses is ‘odd’, strip off the LSB ( the Thumb-mode bit ).
The register values will also change when you use a different optimisation level, -Os in stead of -O0.
I also wonder about the stack during an ISR. Richard knows a lot more about this subject. But I remember that in some ports the stack used in main(), the default application stack, is being recycled and used for ISR stack.
This stack is defined in your linker file xxx.ld:
_estack = 0x20050000; /* end of RAM */
_Min_Stack_Size = 0x460; /* required amount of stack */
In this example, the last 1120 bytes of RAM are dedicated to the stack.